1. Field of the Invention
The present invention relates to a damper device, especially to a damper device arranged in a place where an inputted force for rotary motion or linear motion is transmitted to an output member, and an image forming apparatus such as a copier or a printer.
2. Description of Related Art
Generally, in an electrophotographic image forming apparatus, a rotary drive for an image forming process requires highly-accurate transmission of a rotative force. However, a rotary drive system includes factors of load fluctuations in a rotating direction or vibrations (speed fluctuations) in the rotating direction, such as a motor and engagements between gears, which inhibits an improvement in accuracy of the transmission of the rotative force. Meanwhile, simplification of the system for transmitting a rotative force has been demanded so as to reduce the cost, and for realizing this, vibrations (speed fluctuations) that occur upstream from the drive system need to be effectively blocked by a simple means so as not to be transmitted to downstream.
Japanese Patent Laid-Open Publication No. 2002-174932 describes a drive system including a brushless motor that generates motive power, a photoreceptor drum that is driven to rotate by the motive power of the brushless motor, a gear train that transmits the motive power of the brushless motor to the photoreceptor drum through a plurality of gears, a rubber vibration isolator that is located between the gears so as to prevent transmission of vibrations to the photoreceptor drum, and a photoreceptor gear that is provided in the photoreceptor drum and connected to the gear.
However, the vibration isolating measure described in Japanese Patent Laid-Open Publication No. 2002-174932 is not necessarily preferable in terms of simplification of the structure as well as effects, and a more effective measure to isolate vibrations has been desired.